The present disclosure relates to an armature in a rotary device and a method for manufacturing the same.
There exists a rotary device that includes a yoke in which magnetic poles are provided to an inner peripheral surface by a plurality of sets of permanent magnets and an armature in which a plurality of slots are formed to be axially long in an outer circumferential direction of a core and a plurality of coils are structured such that winding wires that are wound between slots at predetermined intervals are electrically conductive with adjacent commutator segments. When such an electric motor needs to have high torque and be downsized, the electric motor is multipolarized by increasing the number of sets of the permanent magnets, or the number of the commutator segments and the slots are increased so as to respond to the need. A magnetic imbalance, however, occurs when lap winding is carried out between commutator segments around and to which ends of a coil are wound and connected, and parts at which the coil is wound around, with the commutator segments and the parts being axially opposed substantially to each other. Centrifugal whirling is also generated because of torque ripple or the like.
In order to solve the problem, a proposed electric motor is constructed such that the number of the commutator segments is twice as many as the number of the slots. A first winding wire to be conductive with an arbitrary commutator segment and another commutator segment that is adjacent to the arbitrary commutator segment in a circumferential direction is wound in a forward-winding direction around slots that are opposed to a magnetic pole. A second winding wire to be conductive with the arbitrary commutator segment and another commutator segment that is adjacent to the arbitrary commutator segment in another circumferential direction is wound in a reverse-winding direction around slots that are opposed to another magnetic pole. The magnetic balance may thus be improved (see WO2005/036724, for example).